One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,6)(7,8)(9,10)(11,19)(12,16)(13,17)(14,18)(15,21)(20,24)(22,23)(27,35)(28,34)(29,32)(31,37)(36,40)(38,39) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,11)(10,15)(12,20)(13,22)(14,21)(16,23)(17,24)(18,19)(25,26,30,33)(27,36,38,31)(28,29,34,32)(35,40,39,37)(3,7)(5,8)(9,12,14,13)(10,16,18,17)(11,20,21,22)(15,23,19,24)(25,27)(26,31)(28,37)(29,39)(30,38)(32,35)(33,36)(34,40)(2,6)(3,7)(9,13,14,12)(10,17,18,16)(11,20,21,22)(15,23,19,24)(25,28,30,34)(26,32,33,29)(27,37,38,40)(31,35,36,39)(3,7)(5,8)(10,18)(15,19)(16,17)(23,24)(26,33)(27,38)(28,34)(35,39) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.